Two Australians have been "directly affected" by the attack in London.

Prime Minister Malcolm Turnbull has confirmed two Australians have been “directly affected” by the latest terrorist rampage in London.

Three men launched the van and knife attack on London Bridge and at nearby Borough Market just after 10pm on Saturday local time, killing six people. Police shot the terrorists dead within eight minutes of the violence erupting.

In an address to the nation on Sunday, Mr Turnbull said the government was aware of reports of “two Australians who have been directly affected by this attack”.

One was in hospital, with authorities making inquiries about the location of the second, he said.

The families of both victims had been notified.

“Our officials will continue to provide every assistance they can to Australians affected by this shocking attack and their families,” Mr Turnbull said.

The prime minister declared Australia’s “absolute solidarity” with Britain.

“Our prayers and resolute solidarity are today as always with the people of Britain in the face of the shocking terrorist attacks in London,” Mr Turnbull tweeted.

Foreign Minister Julie Bishop said she spoke to UK High Commissioner Alexander Downer shortly after reports of the emergency.

"We have conveyed our condolences to the UK government through our officials," Mr Turnbull said in a subsequent statement.

The prime minister said he had received briefings from the Counter Terrorism Coordinator, the Director General of Security and the deputy AFP commissioner, and had also spoken to Mr Downer.

"Australians should be reassured that our agencies are today, as every day, working relentlessly to keep Australians safe," he added.

Listen: The attack comes as we're still reeling from Manchester. (Post continues after audio.)

Opposition Leader Bill Shorten said he was "shocked and appalled" by yet another attack in England.

"When it comes to fighting terrorism, we are united in this together," he told reporters in Melbourne.

"The more that these things happen the more it makes me realise Australians need to stick together."

He briefly spoke to Labor senator Sam Dastyari who is in London and having dinner very close to where the attack happened.

"He was nothing short of complete praise for the role of the British police force," Mr Shorten said.

Senator Dastiyari described the attack as horrific.

"This literally happened 20 metres from where we were and we could hear it all and were taken past the bodies," he told Nine News.

"There is a lot of fear, confusion, panic, a lot of elderly people being helped and carried. A lot of shock."

If any Australians are concerned about family and friends and unable to contact them they should call 1300 555 135 or +61 2 6261 3305 if overseas, DFAT said.